Return to Question

subroutine bfexec(bfprogram)
begin
 Looping through the bfprogram,
 If(current character is '[')
 Find the corresponding ']'
 Store the code between the two brackets in, say, 'subprog'
 Save the value of the current cell in oldval
 Call bfexec recursively with subprog
 Save the value of the current cell in newval
 If(newval >= oldval)
 Raise an error and exit
 EndIf
 /* Do other character's processings */
 EndIf
 EndLoop
end

subroutine bfexec(bfprogram)
begin
 Looping through the bfprogram,
 If(current character is '[')
 Find the corresponding ']'
 Store the code between the two brackets in, say, 'subprog'
 Save the value of the current cell in oldval
 Call bfexec recursively with subprog
 Save the value of the current cell in newval
 If(newval >= oldval)
 Raise an 'infinite loop' error and exit
 EndIf
 /* Do other character's processings */
 EndIf
 EndLoop
end

SECOND EDIT: I have written what I purport to be infinite loop detector. It probably misses some edge cases (or less probably, somehow escapes Mr. Turing's clutches), but seems to work for me as of now. In pseudocode form, here it goes:

subroutine bfexec(bfprogram)
begin
 Looping through the bfprogram,
 If(current character is '[')
 Find the corresponding ']'
 Store the code between the two brackets in, say, 'subprog'
 Save the value of the current cell in oldval
 Call bfexec recursively with subprog
 Save the value of the current cell in newval
 If(newval >= oldval)
 Raise an error and exit
 EndIf
 /* Do other character's processings */
 EndIf
 EndLoop
end